Ratchet mechanism

ABSTRACT

A ratchet mechanism adapted for use with hand tools having a substantially columnar handle capable of being engageable with the ratchet mechanism, such that the tool handle can be reversibly rotated. The ratchet mechanism is independent of the tool and therefore may be used with any number of different tools having different handle sizes and shapes. The ratchet mechanism of the present invention includes a ratchet wheel rotatably positioned on a base plate and includes a plurality of crescentshaped teeth forming crescent-shaped gaps between the teeth for engaging a pair of pawl elements simultaneously or selectively. Lever means are provided for actuating the pawl elements, which in turn permits the ratchet wheel to rotate clockwise or counterclockwise, or maintains the ratchet wheel in fixed position. The ratchet mechanism further includes a plurality of projecting elements mounted circumferentially above the ratchet wheel. The projecting elements are adapted to engage the end of a tool, thereby imparting rotatable motion thereto.

[ RATCHET MECHANISM [75] Inventor: Max Pasbrig, Orselina, Switzerland Lacreit Brevetti S.A., Via Motta,

[73] Assignee:

' Switzerland [22] Filed: Sept. 20, 1973 [21] Appl. No.: 399,242

[30] Foreign Application Priority Data Oct. 11, 1972 Switzerland 14 891/72 [52] US. Cl 74/575, 74/157, 81/185 [51] Int. Cl..... G05g 1/00 [58] Field of Search 74/575, 577, 157, 156;

81/177 R, 185, 177 A, 177 D; 145/61 L, 77, 70

56] References Cited 9 UNITED STATES PATENTS 2,620,001 12/1952 Fratz et al 81/177 R 2,627,757 2/1953 Austin 74/157 2,711,112 6/1955 Durand 81/185 3,698,267 10/1972 Denney 81/185 Primary Examiner-Wesley S. Ratliff, Jr. Attorney, Agent, or Firm-Werner W. Kleeman [451 Jan. 14, 1975.

T571 ABSTRACT A ratchet mechanism adapted for use with hand tools having a substantially columnar handle capable of being engageable with the ratchet mechanism, such that the tool handle can be reversibly rotated. The ratchet mechanism is independent of the tool and 1 therefore may be used with any number of different tools having different handle sizes and shapes. The ratchet mechanism of the present invention includes a ratchet wheel rotatably positioned on a base plate and includes a plurality of crescent-shaped teeth forming crescent-shaped gaps between the teeth for engaging a pair of pawl elements simultaneously or selectively.

Lever means are provided for actuating the pawl elethe end of a tool, thereby imparting rotatable motion thereto.

7 Claims, 8 Drawing Figures RATCHET MECHANISM This invention relates to a ratchet mechanism for use with screwdrivers, box-spanners or similarly operable tools having a substantially rod-shaped or columnar tool handle mounted on the rear end of the tool shank, the mechanism comprising a ratchet wheel and pawls selectively engageable with said wheel bymeans of a shift-lever.

Ratchet mechanisms built into a screwdriver or similarly operable tool, and more particularly into the handle of such a tool, for the purpose of enabling either the advance or the reversal of the actuating element relative to the operative part of the-tool, are well known. It is a decisive drawback of such known tools that the built-in ratchet mechanism very considerably reduces their load-taking capacity. Besides, the building-in of the ratchet mechanism largely increases the manufacturing costs of such tools.

Hence it is the object of this invention to provide a novel ratchet mechanism which is independent of the tool and which, therefore; if so desired can be used on tool handles of different sizes.

This object is achieved in that the ratchet wheel is as- It is of special advantage if the driver member comprises a number of tongue elements which project from a base along a circular line, preferably in equidistant relationship. Preferably, the tongues are resilient or springy to ensure increased adaptability of the driver member to too! handles of different size and contour. If the driver member is constituted by a shell consisting of resiliently .displaceable rod-like elements, then the adaptability of the driver member can be extended, within limits to practically any handle size and/or shape.

The ratchet mechanism may with advantage be encased within a handle housing designed to enable easy manual handling thereof, a slanted projection or arm extending from the housing increasing very considerably the operability of the tool.

The ratchet mechanism according to the invention is very simple in design and, therefore, it can be manufactured at low cost. Its foremost advantage lies in that it is not inseparably associated with'one specific tool, but can be used selectively on a variety of different tools. This advantage is particularly noticeable if, for instance, a number of spanners on one and the same body of a motor or of any other machine are to be tightened one after the other, by means of a manually operable ratchet. Furthermore, it is of great benefit, that by a suitable design of the housing or casing for the mechanism, the manual effort required for the tool operation can be considerably reduced, compared with the effort required for the operation of a conventional screwdriver, spanner or the like, and this particularly due to the fact that the mounting of the ratchet mechanism inside the handle is sufficiently stable.

The drawing illustrates, by way of example only, an embodiment of the novel ratchet mechanism according to the invention, with a variety of different driver members. In this drawing:

FIG. 1 shows one preferred embodiment of the present invention in side elevation,

FIG. 2 is a plan view of the embodiment of FIG. 1,

FIG. 3 shows the driver member in side elevation,

FIG. 4 is a plan view of the drive member of FIG. 3,

FIG. 5 is a fragmentary plan view which shows the pawls of the mechanism in position for the tool operation in one direction, and

FIG. 6 is a fragmentary plan view which shows the pawls in their position for the tool operation in the opposite direction,

FIGS. 7 and 8 show in longitudinal section two modified forms of the shaped driver member of the ratchet mechanism.

The mechanism comprises a two-part handle housing 1, a shaped driver member 2, and the ratchet mechanism 3. According to FIGS. 1 to 6 the driver member consists of a number of separated driver elements or tongues 10 which project from a circular line on the ratchet wheel 6, the line being concentric with the rotational axis of said wheel. The upper or tip portion 11 of the driver element 10 is of a smaller cross-section than the base portion resulting in a tapered configuration as shown in FIGS. 1 and 3. By means of its central spindle 7 the ratchet wheel 6 is rotatably mounted on a base plate 8. At its periphery the wheel is provided with teeth 6 of substantially crescent-shaped outer contour. The pawls 4 and 5 are adapted to engage, respectively, each into one of two of the likewise substantially crescent-shaped gaps between pairs of consecutive teeth of the wheel 6. The pawls are likewise formed with substantially crescent-shaped engagement ends 4 and 5', respectively. The crescent-shape configuration of the pawl ends, of the teeth of the ratchet wheel 6, and of the gaps between those teeth provide comparatively large engagement surfaces and, consequently, a large loading capacity and adequate power transmission achievable with the mechanism. Besides, such crescent-shaped engagement surfaces possess increased wear resistance.

The pawls are oscillatableabout pivot pins 4" and 5" secured to the base plate 8. The actuation of the pawls is effected by a shift-lever 17, which is likewise oscillatable on a pin relative to the base plate 8 against the action of a spring 16 by which the pawls 4 and 5 are each biased in the direction of the engagement with the respective spring. FIG. 5 shows the pawl 4, and FIG. 6 the pawl 5 in its position of engagement with one of the opposite ends of the spring 16. In FIG. 4 both pawls are shown to be in engagement with the ratchet wheel 6, the lever 17 thus locking the wheel to the base plate, and the tool handle connected with the mechanism against rotation in either direction of rotation.

As shown in FIGS. 7 and 8, the driver member may have a bottom element of its own, such as 12', to which the tongue elements 10 of-the driver are secured. As a rule, however, it is simpler to use the ratchet wheel 6 as the bottom for the driver member.

In the embodiment according to FIGS. 1 to 6 the tongue-like elements 10 of the driver member, arranged on a circular line of the ratchet wheel, are preferably resilient so that they can yield to pressure exerted in radial directions. This permits the establishment of a firm, force-locked engagement of the driver with differently contoured tool handles. Within limits, it also enables securing the ratchet mechanism to tool handles of different sizes (diameters). In order to limit free displacement of the tongues and, additionally, to strengthen their engagement with a tool handle, a band 18 in tension is preferably provided around the tongues near the free ends of the latter. The band 18 may be elastic, if so desired. In lieu of a closed band 18 it is also possible to use an open band which, after placing on the driver member, can effect clamping of the latter onto a tool handle by means of a tensioning eccentric or of an equivalent tightener.

, If the driver member consists of a casing or jacket 12 having a bottom 12, a resilient cushion 13 which, e.g., may be made of foam material, or may be an air cushion or the like and a multitude of displaceable rod-like elements 14 which can be pushed back against the restoring force exerted by the cushion 13, then the adaptability to conventional tool handles 15 (FIG. 8) is practically unlimited.

Obviously, the rod-like elements 14 must be secured against escape from the casing. They are packed into such closely adjacent positions that the torque can be transferred from the ratchet mechanism to a clamped- 1 in tool handle without slip. If so desired, the housing or casing 12 may be made in one piece with the ratchet wheel.

Alternatively, the driver may bemade simple from a tube section adapted, e.g. machined, to-match the contour of conventional tool handles.

What we claim is:

l. A ratchet mechanism for use in connection with a variety of hand tools such as screwdrivers, boxprising a base, a ratchet wheel rotatably secured to said base, a plurality of oscillatable pawls in operative engagement with said ratchet wheel, a shift-lever for actuating said pawls into operative engagement with said ratchet wheel, driver means substantially co-axial with the rotational axis of said ratchet wheel adapted to be mounted on or slipped over the end of a tool handle whereby reversible rotation can be readily imparted to said tool handle during use.

2. A ratchet mechanism as claimed in claim 1, wherein said driver means includes projecting tonguelike elements made of resilient material arranged on a circular line concentric with the ratchet wheel.

3. A ratchet mechanism as claimed in claim 2, wherein the free end portions of said tongue-like elements are inter-connected by a band element in tension, placed on these end portions.

4. A ratchet mechanism as claimed in claim 1 wherein said driver means comprises a number of displaceable parallel rod-like elements arranged in adjacent positions within a casing or jacket, each element being capable of being pushed back against the action spanners and similarly operable hand-tools having a (restoring force) of an elastic cushion or equivalent disposed within said casing or jacket.

5. A ratchet mechanism as claimed in claim 1,

said pawls and said lever means. 

1. A ratchet mechanism for use in connection with a variety of hand tools such as screwdrivers, box-spanners and similarly operable hand-tools having a substantially rod-shaped, columnar or elongated handle mounted on the tool-shank, the mechanism comprising a base, a ratchet wheel rotatably secured to said base, a plurality of oscillatable pawls in operative engagement with said ratchet wheel, a shift-lever for actuating said pawls into operative engagement with said ratchet wheel, driver means substantially co-axial with the rotational axis of said ratchet wheel adapted to be mounted on or slipped over the end of a tool handle whereby reversible rotation can be readily imparted to said tool handle during use.
 2. A ratchet mechanism as claimed in claim 1, wherein said driver means includes projecting tongue-like elements made of resilient material arranged on a circular line concentric with the ratchet wheel.
 3. A ratchet mechanism as claimed in claim 2, wherein the free end portions of said tongue-like elements are inter-connected by a band element in tension, placed on these end portions.
 4. A ratchet mechanism as claimed in claim 1 wherein said driver means comprises a number of displaceable parallel rod-like elements arranged in adjacent positions within a casing or jacket, each element being capable of being pushed back against the action (restoring force) of an elastic cushion or equivalent disposed within said casing or jacket.
 5. A ratchet mechanism as claimed in claim 1, wherein the ratchet wheel has substantially crescent-shaped teeth alternating with tooth-gaps of substantially crescent-shaped contour, and wherein the pawls have end sections which are likewise substantially crescent-shaped for engaging the crescent-shaped gaps of the ratchet wheel.
 6. A ratchet mechanism as claimed in claim 1, wherein said tongue-like elements have tip portions having a smaller cross-sectiOn than its base portion for accommodating tool handles of varying cross-sections.
 7. A ratchet mechanism as claimed in claim 1, further including spring means in operative engagement with said pawls and said lever means. 